If your center caps rattle and wobble when installed, you may want to bend/tune each tab until they firmly grip the wheels. You really need to reinstall them on the rims before you bolt on the wheels, in my experience.
I will also add that these center caps are one of the most poorly engineered aspects of the truck. Who designs a center cap that is half disengaged by bolting the wheel tight, and is so large in diameter that every lug wrench grinds off the paint on the cap? I'm pretty sure they were engineered by the same group that made dim dome lights and shaky, small FJ60 outside rear view mirrors. The land of misfit Toyota engineers.